Masters Theses

Date of Award

5-2000

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

James D Godkin

Committee Members

Judith M. Grizzle, F. Neal Schrick

Abstract

The purpose of this study was to characterize the cell specific expression of retinoid binding proteins and determine their possible role in retinol transport in the bovine ovary. Cattle ovaries were analyzed for the presence of RBP and CRBP using immunohistochemical procedures. Ovaries were fixed in Bouin's fixative, embedded in paraffin, and treated with specific antibodies for RBP and CRBP. Retinol-binding protein was immunolocalized to the theca and granulosa layers of antral follicles and the granulosa cell layer of some preantral follicles. Cellular retinol-binding protein exhibited intense immunostaining in granulosa cells of preantral and early antral follicles. Retinol-binding protein was found within the stroma and blood vessels. Cellular retinol binding protein was not found within theca cell layers of antral follicles, stroma, or blood vessels. Follicular fluid from small (< 5mm), medium (6-9mm), and large (> 10mm) follicles was aspirated and analyzed for retinol, RBP, and steroid concentrations. Retinol concentrations were found to be significantly higher in the follicular fluid of large follicles compared to small follicles. Retinol-binding protein concentrations in follicular fluid was not significantly different among follicle sizes. Retinol-binding protein was negatively correlated with retinol in the follicular fluid of large follicles but highly correlated with retinol in the follicular fluid of small follicles. The follicular fluid of large follicles had significantly higher amounts of estradiol 17-β than the follicular fluid of medium and small follicles. Estradiol 17-β concentrations were positively correlated with retinol in the follicular fluid of all three follicle sizes. Follicular fluid concentrations of progesterone showed no significant differences among follicle sizes. Progesterone was found to be moderately correlated with estradiol 17-β and RBP concentrations of small follicles and negatively correlated with retinol in the follicular fluid of large follicles. This study demonstrates that RBP, found within healthy, mature follicles, may serve to deliver retinol to the oocyte. CRBP, present in immature, growing follicles, may indicate an important role in retinol storage or in follicular development. Retinol, reflected by estradiol 17-β levels, may be transported in increased amounts by RBP to mature follicles and serve as an indicator of follicular quality.

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